Torsion-spring



A. R. BECKERT.

TORSIONVSPRING.

APPUCATION man OCT. 21. 1919.

' Inventor: Alber- RBec art,

by His Attorngy.

moved by the um'rso s'rarss PATENT OFFICE.

ALBERT B. BECK E B'IXOI LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

TORSION-SPRING.

Specification .1 Lettersratent.

Patented Aug. 9, 1921.

To all whom. it may concern:

Be it known that I, ALBERT R. Bnoxnn'r, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Torsion-Springs, ofwhi'ch thefollowing is a specification.

My invention relates to torque producing members which are also utilized for carrying a current. Such members, for example, are utilized in the ordinary electric measuring instruments for theelement necessary to produce a torque opposed to the torque of the operating elements of the motor, and usually designated as a torsion spring. These torque producing elements are in some classes of instruments used for carr ing in the current to the member adapted to be action of the instrument. The use of my device in this connection is merely illustrative, since'it may eventually be utilized in any other relation where anelectric conductor is adapted to be flexed or strained during its normal operation at frequent intervals. I

A serious problem which confronts the designer of a conductor embodying the functions which are stated above, is that involved in making the conductor sufliciently resilient so as to enable the instrument to be operated repeatedly without any deterioration of the material due to vibrations, etc.,

and also in havlng the conductivity of the member sufficiently low so that there be no undue loss due to the flow of current init. I have succeeded in producing an element fulfilling all of the above requirements in a simple and eflicient manner. In my device I employ a conductor made of two different metals; one of them of high resilience disposed in such a relation as to receive the maximum stress, while the other is a metal of high conductivity so located as to receive a minimum stressand carrying most of the current.

, By way of example I have illustrated in the accompanying drawings one embod iment' of my device in a torsion spring used for an electrical measuring instrument. Fig. "1 of the drawing is an enlarged sectional view of a composite conductor during one'stage of its manufacture; Fig. 2 is an enlarged cross section of the same conductor at a later stage l of manufacture, and Fig. 3 shows, on an en- 7 spiral spring is larged scale, the conductor bent in the form of a" spiral spring and used in the manner that I have indicated above.

Referring now more particularly to the drawing, the hollow metallic casing 11 is made of highly resilient material. For this purpose, I have found, for example, that phosphor bronze is well adapted, fibut other metals possessing the necessary qualities may also be used. .This hollow metal eas mg is disposed around an inner core or wire 12 composed of a metal having high conductivity. This metal may be of copper, for exa'mple,'which, although not resilient, possesses the. necessary conducting properties. The relative ratio of the cross sections of the outer memberll and the inner core 12 is so chosen as to give the right degree of, resilience with the right amount of conductivity. When .this 'compound conductor is to be used as a spiral torsion spring for an instrument it is preferably flattened out by passing it between rollers. This, treatment causes the compound conductor to assume the shape shown in Fig. 2. When this has been done it is an eas matter to wind a given length of this ma- .terial into a flat spiral spring 13 of the sort shown in Fig. 3. In this latter figure the shown as securely attached at its inner end to a spindle 14. The stationary post 15 is shown with a fastening screw 16 to illustrate by way of example how the outer end of the spiral spring may be a propriately. anchored.

y compound conductor is of a peculiar utility in connection with electric measuring instruments, since in this class of work the torsionv spring must be of great uniformity and have suflicient resilience so that it may be flexed a very large number of times without receiving a permanent set; At'the same time it is extremely important that the resistance be maintained as low as possible, since a dead loss in energy results from the Pr loss in the leading-in conductor. Copper itself would make a good spiral spring'as does not possess sufficient resilience to opfar as its conductivity is concerned, but it erate eflicientl as a retardingtorque producing member. nthe same way a springmade wholly ofphosphor bronze would fulfill the requirements as regards resilience but its conductivity would be entirely too 'low.

In the past alloys have been used which have a comparatively low resistance but which have not the requisite resilience needed for this class of work. By making use of my compound conductor for these retarding torque producing springs, I combine the advantages of a resilient material and a conducting material. As shown in the drawings, resilient material is disposed exteriorly so that it takes the maximum stress when the spring is flexed, while the inner core is only slightly stressed. It has been found, by a comparison of spiral springs made respectively of solid phosphor bronze and of a compound material, when the retarding tor ques of both springs are the same for the same deflection, that the resistance of the phosphor bronze spring is more than three times as great as that of the compound spring described in this application.

The advantages I secure by this mode of construction are not limited to instrument springs but are present when the same sort of service is required of an electric conductor; namely, to serve also as a torque producing means, or when such. conductor is adapted to be flexed for long intervals and a large number of times.

\Vhile I have shown inthe accompanying drawings the preferred embodiment of my device, my invention'is not limited thereto, and I aim in the appended claims to embrace all modifications falling fairly within the scope of my invention.

What I claim as new and desire tosecure by Letters Patent of the United States, is,-

1. A torsion spring adapted to serve both as a torque producing means and as an electrical conductor, comprising a comparatively thin casing of highly resilient material, and an inner coreof highly conducting material.

2. A torsion spring for an electrical measuring instrument adapted to serve both as a torque producing means and as an electrical conductor, comprising a casing of highly resilient material, the cross section of-which is a hollow oval, and a core completely filling said hollow casing, of highly conducting material. 7

In witness whereof, I have hereunto set my hand this 17th day of October, 1919.

ALBERT R. BECKERT. 

